Imaging device and imaging method

1. An imaging device, comprising: an image sensor, having a plurality of pixels comprising a first pixel group and a second pixel group arranged in a two dimensional array, and a plurality of A/D converters for simultaneous and parallel conversion of output signals that have been respectively formed by pixels corresponding to the first pixel group and the second pixel group to respective digital signals; an image signal readout section for respectively independently reading out image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor; a flicker detection section for subjecting a subject image that has been formed on the image sensor to photoelectric conversion based on a periodic flicker action of the light source included in the subject, and detecting flicker period of the light source by detecting bright states and dark states of an entire taken image from image output corresponding to pixels corresponding to the second pixel group; and a flicker correction section for, when, in the flicker detection section, an image that has been acquired using pixels corresponding to the second pixel group has light of a bright state and a dark state incident as a result of periodic flicker, making brightness output of a taken image using the first pixel group arranged in correspondence with the second pixel group become a standard brightness output, and correcting brightness output gain corresponding to each pixel of a plurality of pixels corresponding to the first pixel group.

2. The imaging device of claim 1 , wherein: the image signal readout section reads out image signals of the second pixel group within a readout period for image signals of one frame of the first pixel group; the flicker detection section detects flicker frequency of the light source based on a number of flicker frames that occur periodically, using image signals of the second pixel group; and the flicker correction section carries out gain correction of image signals for the first pixel group that have been read out within a period that includes the readout period for the second pixel group.

3. The imaging device of claim 2 , wherein: the flicker detection section further comprises a flicker determination section for determining a flicker state that is occurring in acquired images from the first pixel group; the flicker determination section determines whether or not surface flicker is occurring in acquired images from the first pixel group by detecting flicker frequency of a light source based on number of flicker frames that occur periodically, and comparing a readout period of images composed of the first pixel group with the detected flicker frequency of the light source; and the flicker correction section, in the event that it is determined as a result of determination by the flicker determination section that there is surface flicker in acquired images from the first pixel group, carries out unified gain correction on brightness output of image signals that have been read out from the first pixel group in a time corresponding to images that have been read out from the second pixel group.

4. The imaging device of claim 2 , wherein: the flicker detection section further comprises a flicker determination section for determining a flicker state that is occurring in acquired images from the first pixel group; the flicker determination section determines whether or not line flicker is occurring in acquired images from the first pixel group by detecting flicker frequency of a light source based on number of flicker frames that occur periodically, and comparing a readout period of images composed of the first pixel group with the detected flicker frequency of the light source; and the flicker correction section, in the event that it is determined as a result of determination by the flicker determination section that line flicker is occurring in acquired images from the first pixel group, carries out brightness gain correction within the frame, on brightness output of each frame image signal that has been read out from the first pixel group, arranged corresponding to images that have been read out using the second pixel group.

5. The imaging device of claim 2 , wherein: the image signal readout section further comprises a frame rate setting section for setting frequency of reading out image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor; and the frame rate setting section sets frame rates, that are frequencies for reading out respective image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor, to frame rates that are respectively different readout frequencies for at the time of movie shooting and at the time of live view display, and sets respective frame rates for at the time of movie shooting to frame rates that are faster than respective frame rates at the time of live view display.

6. The imaging device of claim 3 , wherein: the image signal readout section further comprises a frame rate setting section for setting frequency of reading out image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor; and the frame rate setting section sets frame rates, that are frequencies for reading out respective image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor, to frame rates that are respectively different readout frequencies for at the time of movie shooting and at the time of live view display, and sets respective frame rates for at the time of movie shooting to frame rates that are faster than respective frame rates at the time of live view display.

7. The imaging device of claim 4 , wherein: the image signal readout section further comprises a frame rate setting section for setting frequency of reading out image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor, and the frame rate setting section sets frame rates, that are frequencies for reading out respective image signals from pixels corresponding to the first pixel group and the second pixel group of the image sensor, to frame rates that are respectively different readout frequencies for at the time of movie shooting and at the time of live view display, and sets respective frame rates for at the time of movie shooting to frame rates that are faster than respective frame rates at the time of live view display.

8. An imaging method for an imaging device, comprising: a step of respectively independently reading out image signals from pixels corresponding to a first pixel group and a second pixel group, from an image sensor having a plurality of pixels comprising the first pixel group and the second pixel group arranged in a two dimensional array, and a plurality of A/D converters for simultaneous and parallel conversion of output signals that have been respectively formed by pixels corresponding to the first pixel group and the second pixel group to respective digital signals; a flicker detection step of subjecting a subject image that has been formed on the image sensor to photoelectric conversion based on a periodic flicker action of a light source included in the subject, and detecting flicker period of the light source by detecting bright states and dark states of an entire taken image from image output corresponding to pixels corresponding to the second pixel group; and a flicker correction step of, when, in the flicker detection step, an image that has been acquired using pixels corresponding to the second pixel group has light of a bright state and a dark state incident as a result of periodic flicker, making brightness output of a taken image using the first pixel group arranged in correspondence with the second pixel group become a standard brightness output, and correcting brightness output gain corresponding to each pixel of a plurality of pixels corresponding to the first pixel group.